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Microbial cross-contamination remains an on-going challenge in the food sector despite implemented sanitation programs. Antimicrobial coatings with inherent self-sanitizing properties have been explored to enhance current cleaning practice and support food safety. Prior work has demonstrated successful incorporation of dual antimicrobial characters, cationic polymers and N-halamines, into one coating system. In addition to the rechargeable nature of N-halamines, the coating was reported to exhibit biocidal effects due to the inherently antimicrobial cationic moieties and the chlorinated N-halamines. However, while these polymer coatings were able to retain antimicrobial activity after repeated chlorination, signs of hydrolysis was observed for the N-halamine bonds, indicating potential issues for long-term usage. Herein, we introduced varied molecular weight cross-linkers in an adaption of the established fabrication method to evaluate cross-linker molecular weight (styrene maleic anhydride (SMA) of 6, 8, 120, 250 kDa) influence on surface properties of the coating. All antimicrobial polymer coatings exhibited similar FTIR spectra, with a prominent absorption band at ~1650 cm-1 suggesting successful cross-link of the polyethyleneimine and SMA. Surface concentration of primary amines ranged from 350-900 nmol/cm2, and N-halamines from 90-130 nmol/cm2. Surface energy decreased with increasing molecular weight of SMA, but were not statistically different from one another. In the end, optimal cross-linker molecular weight was determined based on antimicrobial performance, where the coated PPs with 6 kDa SMAs demonstrated enhanced biocidal effects against E. coli O157:H7 in its chlorinated form. Further, the antimicrobial coating demonstrated efficacy of ~3 to >5 log reductions of microbial load in its unchlorinated and chlorinated form against E. coli O157:H7, L. monocytogenes, and P. fluorescens. Storage studies support the stability of the chlorinated halamines, with full retention of chlorinated N-halamines over a 24 h study (representative of time between sanitation cycles). These results support the potential application of this antimicrobial polymer coating in food processing and handling operations, in support of reducing cross-contamination of spoilage and pathogenic microorganisms.

La surface d'un matériau est le lieu privilégié des interactions entre le matériau et son environnement. La technique couche-par-couche, qui consiste en un dépôt alterné de polyanions et de polycations, ouvre de nouvelles perspectives dans le domaine des biomatériaux pour le contrôle de ces interactions. La cohésion des films multicouches de polyélectrolytes est principalement assurée par des interactions électrostatiques mais a été étendue à d'autres forces motrices telles que les interactions hôte-invité. Nos travaux s’articulent autour de deux axes principaux. D’une part, nous nous sommes intéressés aux films multicouches de polymères neutres basés sur des interactions hôte-invité et en particulier à l'influence de la force du complexe d’inclusion b-cyclodextrine/ferrocène sur la topographie de ces films. La force de l’interaction hôte-invité a d’abord été modulée en associant différents invités (l’adamantane, le ferrocène et le pyrène) avec la β-cyclodextrine. La force du complexe b-cyclodextrine/ferrocène a été ensuite modulée par la présence de différents sels de sodium à différentes forces ioniques au cours de la construction du film. Une force d'interaction intermédiaire du complexe semble être nécessaire pour former des films continus, tandis que, si elle est trop faible, la force d'interaction limite la construction du film.D’autre part, motivé par le fait que la prévention des infections microbiennes des dispositifs médicaux implantables constitue un problème médical et financier majeur, nous avons développé de nouveaux revêtements antimicrobiens grâce à la technique couche-par-couche. Des films multicouches à base de polysaccharides contenant la cateslytine, un peptide antimicrobien, permettent l’inhibition en 24h du développement de Candida albicans et Staphylococcus aureus, qui sont des agents pathogènes communs et virulents rencontrés dans les maladies nosocomiales. La libération des peptides antimicrobiens est déclenchée par la dégradation enzymatique du film en présence des agents pathogènes. Le revêtement est ainsi qualifié d’auto-défensif. La non-cytotoxicité du film vis-à-vis des cellules humaines permet une application cliniquement pertinente pour prévenir les infections sur les cathéters. Des dimères à base de cateslytine de différentes longueurs et un dendrimère ont été synthétisés afin d'améliorer l'activité biologique du peptide d'origine, i.e. ses propriétés antimicrobiennes et antiinflammatoires. Afin d’élaborer des films antimicrobiens mécaniquement robustes, le polyuréthane (polymère entrant dans la composition des cathéters) a été fonctionnalisé par une couche de polydopamine qui peut ensuite réagir avec des groupements thiol ou amine, permettant la fixation covalente des films de polysaccharides antimicrobiens réticulés étape par étape. / The surface of a material is the privileged location, where the interactions between the material and its environment take place. In the field of biomaterials, the challenge is to control these interactions. A very versatile coating technique is the layer-by-layer deposition, which consists in the alternated deposition of polyanions and polycations. The cohesion of polyelectrolyte multilayer films is primarily ensured by electrostatic interactions but was extended to other driving forces such as host-guest interactions. Our work was constituted of two main parts.In the first part, the buildup of neutral polymer multilayer films based on host-guest interactions was studied and in particular the influence of β-cyclodextrin/ferrocene interaction strength on the topography of these films. The host-guest interaction strength was first modulated by involving different guests (adamantane, ferrocene and pyrene) in the buildup. Then, β -cyclodextrin/ferrocene interaction strength was tuned by the presence of different types and concentrations of salts during the multilayer buildup. Intermediate interaction strength seems to be required to form continuous films, whereas, if too low, the interaction strength limits the film buildup.In the second part, motivated by the fact that the prevention of pathogen colonization of implantable medical devices constitutes a major medical and financial issue, polyelectrolyte multilayers were used as tools to develop new antimicrobial coatings. Polysaccharide multilayer films containing cateslytin, an antimicrobial peptide, fully inhibited in 24h the development of Candida albicans and Staphylococcus aureus, which are common and virulent pathogens agents encountered in care-associated diseases. The release of the antimicrobial peptides was triggered by the enzymatic degradation of the film due to the pathogens themselves introducing the concept of self-defensive coating. The non-cytotoxicity of the film, towards human cells, highlights a medically relevant application to prevent infections on catheters. Different cateslytin based dimers with various lengths and one dendrimer were synthesized in order to improve the bioactivity of the original peptide, i.e. antimicrobial and anti-inflammatory properties. In order to obtain mechanically robust antimicrobial films, polyurethane (polymer that composes catheters) was functionalized with a polydopamine layer that can further react with thiol or amine groups, allowing the covalent attachment of step-by-step cross-linked antimicrobial polysaccharide films.

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